class Screen(object):
    @property
    def width(self):
        return self._width

    @width.setter
    def width(self, value):
        self._width = value

    @property
    def height(self):
        return self._height

    @height .setter
    def height(self, value):
        self._height  = value

    @property
    def resolution(self):
        return self._height * self._width


a = Screen()
a.width = 1024
a.height = 768
print(a.width,a.height,a.resolution)
s = Screen()
s.width = 1024
s.height = 768
print('resolution =', s.resolution)
if s.resolution == 786432:
    print('测试通过!')
else:
    print('测试失败!')